Update MD025/single-title to ignore preceding blank lines and comments when looking for a title (top-level heading) (fixes #1420).

test/heading-multiple-top-level-preceding-blank-and-comment.md

@@ -0,0 +1,6 @@
+
+<!-- Comment -->
+
+# Heading 1
+
+# Heading 2 {MD025}

test/heading-multiple-top-level-preceding-blank.md

@@ -0,0 +1,4 @@
+
+# Heading 1
+
+# Heading 2 {MD025}

test/heading-multiple-top-level-preceding-comment.md

@@ -0,0 +1,4 @@
+<!-- Comment -->
+# Heading 1
+
+# Heading 2 {MD025}

test/snapshots/markdownlint-test-scenarios.mjs.md

@@ -15750,6 +15750,92 @@ Generated by [AVA](https://avajs.dev).
       `,
     }
 
+## heading-multiple-top-level-preceding-blank-and-comment.md
+
+> Snapshot 1
+
+    {
+      errors: [
+        {
+          errorContext: 'Heading 2 {MD025}',
+          errorDetail: null,
+          errorRange: null,
+          fixInfo: null,
+          lineNumber: 6,
+          ruleDescription: 'Multiple top-level headings in the same document',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md025.md',
+          ruleNames: [
+            'MD025',
+            'single-title',
+            'single-h1',
+          ],
+        },
+      ],
+      fixed: `␊
+      <!-- Comment -->␊
+      ␊
+      # Heading 1␊
+      ␊
+      # Heading 2 {MD025}␊
+      `,
+    }
+
+## heading-multiple-top-level-preceding-blank.md
+
+> Snapshot 1
+
+    {
+      errors: [
+        {
+          errorContext: 'Heading 2 {MD025}',
+          errorDetail: null,
+          errorRange: null,
+          fixInfo: null,
+          lineNumber: 4,
+          ruleDescription: 'Multiple top-level headings in the same document',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md025.md',
+          ruleNames: [
+            'MD025',
+            'single-title',
+            'single-h1',
+          ],
+        },
+      ],
+      fixed: `␊
+      # Heading 1␊
+      ␊
+      # Heading 2 {MD025}␊
+      `,
+    }
+
+## heading-multiple-top-level-preceding-comment.md
+
+> Snapshot 1
+
+    {
+      errors: [
+        {
+          errorContext: 'Heading 2 {MD025}',
+          errorDetail: null,
+          errorRange: null,
+          fixInfo: null,
+          lineNumber: 4,
+          ruleDescription: 'Multiple top-level headings in the same document',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md025.md',
+          ruleNames: [
+            'MD025',
+            'single-title',
+            'single-h1',
+          ],
+        },
+      ],
+      fixed: `<!-- Comment -->␊
+      # Heading 1␊
+      ␊
+      # Heading 2 {MD025}␊
+      `,
+    }
+
 ## heading_duplicate_content.md
 
 > Snapshot 1